diff --git a/src/tuimble/app.py b/src/tuimble/app.py
index 18520b5..084b02d 100644
--- a/src/tuimble/app.py
+++ b/src/tuimble/app.py
@@ -56,7 +56,7 @@ class StatusBar(Static):
     server_info = reactive("")
 
     def render(self) -> str:
-        w = self.size.width if self.size.width > 0 else 80
+        w = self.content_size.width if self.content_size.width > 0 else 80
 
         if self.connected:
             conn_sym = "[#9ece6a]\u25cf[/]"
@@ -106,8 +106,10 @@ class ChannelTree(Static):
 
     @property
     def _available_width(self) -> int:
-        """Usable character width, accounting for padding."""
-        w = self.size.width if self.size.width > 0 else self.DEFAULT_WIDTH
+        """Usable character width (content area, excludes padding/border)."""
+        w = self.content_size.width
+        if w <= 0:
+            w = self.DEFAULT_WIDTH
         return max(w, 12)
 
     @staticmethod
@@ -203,12 +205,10 @@ class TuimbleApp(App):
         height: 1fr;
     }
     #sidebar {
-        width: auto;
-        min-width: 16;
-        max-width: 32;
+        width: 24;
         border-right: solid #292e42;
         padding: 0 1;
-        overflow: hidden;
+        overflow-x: hidden;
     }
     #chat-area {
         width: 1fr;
@@ -429,9 +429,10 @@ class TuimbleApp(App):
 
     # -- resize --------------------------------------------------------------
 
-    def on_resize(self, _event: events.Resize) -> None:
-        """Refresh width-aware widgets when terminal resizes."""
-        self.query_one("#sidebar", ChannelTree).refresh()
+    def on_resize(self, event: events.Resize) -> None:
+        """Adapt layout to new terminal dimensions."""
+        sidebar = self.query_one("#sidebar", ChannelTree)
+        sidebar.styles.width = max(16, min(32, event.size.width // 4))
         self.query_one("#status", StatusBar).refresh()
 
     # -- lifecycle -----------------------------------------------------------